The present invention relates to a process and device for stopping a printing operation upon reception of abnormal image data in a facsimile telecommunications system, and more particularly, to a process and device for stopping a printing operation upon reception of a predetermined number of consecutive black data lines.
Generally, a facsimile telecommunications system receives image data by executing a system protocol after a ring signal has been detected, or by scanning a document upon input of a copy key. Protocol sets rules for the interaction of transmission and reception of units of telecommunications equipment, that are usually implemented through the programming of the data terminal equipment involved rather than being built into the hardware. In a plain paper facsimile system dedicated to printing image data onto cut sheets of a printable medium such as paper, a developing unit including an expendable organic photosensitive OPC drum, and a toner hopper supplying toner are designed to be exchanged when depleted to a point of use in excess of a predetermined limit of usage. After the image data is received, an operation for printing the image data is executed. With a plain paper facsimile, a consumable developing unit is often utilized. This developing unit typically includes an organic photoconductive (OPC) drum and a toner hopper for storing toner. After the developing unit is used to generate a given number of printed sheets, it should be exchanged for a new one so that proper printing operations can be continued.
When by mistake a user erroneously transmits a document with an upside down orientation from a facsimile telecommunications unit, and the back surface of the document exhibits a color of a given degree of darkness, the receiving facsimile will interpret and print the received image data as a continuous stream of black image data (i.e., all lines are composed of black dots). Accordingly, the receiving facsimile expends a large quantity of toner in order to print the black image data. We have found that since the developing unit should be exchanged after a given amount of use, these types of situations are particularly troublesome in terms of unnecessarily useless toner depletion. Moreover, when an expended developing unit is continually used in a facsimile system employing a thermal print head (TPH), a problem arises in that the thermal print head (TPH) becomes overheated, thereby causing damage to the facsimile system.
Another problem that occurs in facsimile telecommunications systems from transmission of telecommunications data attributible to an upside down sheet of paper is the unnecessary consumption of sheets of paper. One recent effort that attempts to addresses the issue of paper conservation is U.S. Pat. No. 5,493,421 entitled Facsimile Apparatus issued to Uetama et al. In Uetama et al. '421, when blank line data representative of a predetermined number of blank lines (i.e., the entire line is composed of white dots) is received successively, then printing control means produces an output omitting the blank line data. As a result, the blank line data, which may represent margins or the like, is omitted in printing. While this type of conventional art is useful for conserving recording sheets in a facsimile telecommunications system, we note that it fails to address the problem of unnecessary toner consumption.